You may be putting your running shoes on to keep fit but it may be doing more harm to the environment than you may think.
According to researchers at the Massachusetts Institute of Technology (MIT), a new pair of typical running shoes generates 30 pounds of carbon emissions, equivalent to keeping a 100-watt light bulb switched on for one week.
Their research revealed more than two thirds of the carbon impact came from manufacturing plants and only a small portion from extracting raw materials. A significant proportion of the world’s shoe manufacturers are in China, where coal is the dominant source of electricity. It is also used to generate steam or run other processes in the plant itself.
A typical pair of running shoes comprises of 65 discrete parts requiring more than 360 processing steps to assemble, from sewing and cutting to moulding, foaming and heating. The researchers found that for these small, light components such processes are energy intensive – and therefore carbon intensive – compared to the energy that goes into making shoe materials like polyester.
Randolph Kirchain, Principal Research Scientist in MIT’s Materials Systems Laboratory said the research could help shoe designers identify ways to improve designs and reduce shoes’ carbon footprint. He added the findings could also help industries assess the carbon impact of similar consumer products more efficiently.
“Understanding environmental footprint is resource intensive. The key is, you need to put your analytical effort into the areas that matter. In general, we found that if you have a product that has a relatively high number of parts and process steps and that is relatively light [weight], then you want to make sure you don’t overlook manufacturing,” he said.
Nearly 25 billion shoes were purchased around the world in 2010, the majority of them manufactured in China and other developing countries.